How Many Wires in a Receptacle Outlet Box

How to Install Wiring into an Outlet Box: Box Fill Calculation for Electrical Outlet Box. Guide for Installing electrical wires into an outlet box.

Electrical Wires in a Outlet BoxElectrical Question: How do I install electrical wires into an outlet?

I have plastic Carlon blue shallow old work boxes that are labeled as having 17 cubic inches. I am hoping to use these boxes in shallow walls in my kitchen which has 2×3 framing.

Do the poke through tabs that pinch the wires in the box count as internal clamps that need to be accounted for in doing box fill calculations? They are a molded part of the box and pinch the wire in place.

The box says I can get seven 12 gauge box fill conductors in the box.

With a cable going in the box and one going out to another receptacle, I have four conductors.

Each receptacle counts two conductors.

The ground wires count as one.

That gives me seven conductors in the box fill calculations and at 12 gauge I am under 17 cubic inches.

If those little pinching tabs count as internal clamps, however, that puts me at 8 conductors and over the box fill limit for the box.

So to sum up, do those pinching tabs needed to be counted in these boxes? Using this box with 17 cubic inches can I get two 12 gauge cables and a receptacle in and not violate box fill?

How to Install Wiring into an Outlet Box

Application: Electrical Wiring for Receptacle Outlets.
Skill Level: Intermediate to Advanced – Best performed by a Licensed Electrician.
Tools Required: Electricians Pouch of Hand Tools for Rough-In Wiring, Electric Drill and Auger Bits and Extension Cord.
Estimated Time: Depends on the extent of the bathroom remodel project, the type of construction and available access to the project area.
Precaution: Any existing wiring in the immediate area that may interfere with the installation of new construction materials should be identified, turned OFF and Tagged.
Notice: Modifying existing wiring or installing additional bathroom electrical wiring should be done according to local and national electrical codes with a permit and be inspected.

Box Fill Calculation for Electrical Outlet Box

Example: Guide for Installing Electrical Wires into an Outlet Box.

According to NEC 314.16(B) there is no allowance for small fittings, and because these clamps are an internal part of the box then they are included into the calculation as provided by the box manufacturer.

If the box states the allowed number of conductors per wire gauge, then the box is already taking into account the built in clamps.

With this 17 cubic inch box and the information that is supplied with the box you should have enough space for your wires and a receptacle for each box.

Electrical Junction Boxes for Home Wiring

Understanding electrical junction boxes and what they are used for. Home electrical wiring is the process of installing electrical wire to a location that will serve electrical devices or an appliance. One very important component is the box where the wire will be installed.

The type and size of the home wiring electrical boxes will depend upon the circuit size, application and its location.

Trademark Copyright Information
Part P - Electrical Safety is registered Crown Copyright of the UK Government Planning Department for Communities
CE and Canadian Electrical Code CSA C22.1 are registered trade marks of the Canadian Standards Association (CSA)
NEC and National Electrical Code are registered trade marks of the National Fire Protection Association (NFPA)